In mail processing machines, such devices are used, in particular, for manual or automatic envelope stuffing. They can also be used for detecting that envelopes have indeed been stuffed prior to closure and franking, or that the flaps of stuffed envelopes have been unfolded prior to dampening the gummed portions of the flaps for closure purposes.
In mail processing machines, envelopes are taken one by one from a magazine in which they are stacked with their flaps folded against their bodies. The envelopes are taken by an unstacking machine which applies them to a conveyor at its outlet, with the envelopes being presented separate from one another and being delivered to a processing station, for example a station where the envelopes are opened for subsequent stuffing.
The presentation of open envelopes assists an operator if the envelopes are being stuffed manually, and is essential in mail processing machines that perform stuffing automatically.
French patent publication No. 1 584 973 describes a transporter device for envelopes, for the purposes of automating the separating, the opening, the stuffing, the dampening, and the closing of envelopes. In particular, elements are provided on the path of envelopes coming separate from one another from a magazine in order to open the flaps of said envelopes.
These elements are constituted by two pairs of rolls which are disposed one after the other so that each envelope arriving base foremost is engaged at a given moment between said two pairs of rolls, and a hinged lever then applies a considerable curve to the envelope held between the pairs of rolls in order to separate the flap from the body of the envelope. This envelope curvature is assisted by the downstream pair of rolls on the envelope path giving the envelope a lower speed than that given by the upstream pair of rolls. A blade disposed upstream from the downstream pair of rolls holds the flap so as to open the envelope fully.
In such devices where the top edge of the envelope (i.e. the edge with the flap attached thereto) is situated on the rear of the envelope path, there are problems of reliability in operation related to the risks of envelopes jamming or being damaged by virtue of their flaps hanging ajar prior to the envelopes being deliberately curved in order to enable the flaps to be held by the blade.
The aim of the present invention is to provide a very highly reliable device for opening envelopes at a high rate matching an envelope-stuffing rate, said device, in addition, being compact and easily integrated in mail processing machines regardless of the type of envelope unstacker that may be used.